Certain foods are perishable materials which are susceptible to mold, yeast, or fungal growth. Mold, yeast, or fungal growth in such foods can drastically reduce the usable life span of the foods. For example, dairy products, particularly cheese, and meat products, particularly fermented meat products such as sausages and pepperoni, are especially susceptible to being rendered unfit to eat by the growth of molds, yeast, and fungi.
Anti-mycotic materials are materials which inhibit mold, yeast, and fungal growth. Anti-mycotic materials are commonly added to perishable foods susceptible to mold, yeast, or fungal growth to inhibit the growth of such materials in the food and extend the shelf-life of the foods.
Anti-mycotic materials which are added to foods to extend the usable life span of the foods act by either an indirect or a direct mechanism to inhibit the growth of molds, yeasts and fungi. Indirect action anti-mycotics are materials such as enzyme/carbohydrate mixtures which react in combination with oxygen in a sealed package of food to scavenge and deplete oxygen in the package containing the anti-mycotic mixture, thereby inhibiting the growth of oxygen dependent molds, yeast, and fungi. Direct action anti-mycotics are materials applied in or on a food which inhibit the growth of a mold, yeast, or fungus upon direct contact with the mold, yeast, or fungus, often by inhibiting the development of mold, yeast, or fungus cell membranes. Direct action anti-mycotic materials are often preferable to indirect action anti-mycotics since indirect action anti-mycotics are only effective while a food material remains sealed in a package, and do not provide continuing anti-mycotic protection after the package of food is opened.
A particularly preferred direct action anti-mycotic is natamycin. Natamycin is one the few direct action anti-mycotics which is approved as a food additive by the Food and Drug Agency of the U.S. government. Natamycin is commercially available, for example as Delvocide.RTM. from Gist-Brocades Food Ingredients, Inc., King of Prussia, Pa. 19406, or as Natanaxe.RTM. from Cultor Food Science (address). Commercially available natamycin may be obtained in a pure form, or may be cut with a diluent such as lactose or sodium chloride.
Natamycin materials are active at relatively low concentrations. In an agar medium natamycin has been shown to have anti-mycotic activity at concentrations upwards from 1 part per million ("ppm"). In an animal feed mixture, U.S. Pat. No. 5,902,579 discloses that 1.1-110 ppm of the anti-mycotic natamycin can be provided in the feed mixture in a fermentation biomass.
Prior to the present invention, however, concentrations of greater than 5 ppm of natamycin have been necessary for effective mold, yeast, and fungus control in non-liquid foods for human consumption, in part since conventional natamycin which is fit for human consumption does not have sufficient anti-mycotic activity to prevent mold, yeast, or fungal growth when spread uniformly at very low concentrations in the food material. In the dairy industry, for example, concentrations of greater than 5 ppm, typically from 6 ppm to 20 ppm, of natamycin are required to provide effective protection of a dairy food such as cheese from spoilage due to mold, yeast, or fungus growth.
It is desirable to provide a natamycin material which has effective anti-mycotic activity at very low concentrations. Natamycin is an extremely expensive commodity, and reduction of the amount required for effective anti-mycotic activity in a food fit for human consumption offers significant cost advantages.